Burgruine Vienenburg, Medieval castle ruin in Goslar, Germany.

Burgruine Vienenburg is a medieval castle ruin in Goslar that rises from a hilltop overlooking the town with surrounding defensive walls. The most striking element is a round tower that stands above the lower ruins of the palace structures and can be seen from considerable distance.

The castle was first mentioned in 1306, when Count Burchard issued a document here; its builder is thought to be Count Burchard VII of Wernigerode, acting for the Hildesheim bishop Siegfried II. It was pledged to Goslar in 1341, passed to the bishops of Hildesheim in 1367, and was ceded to Duke Henry II of Brunswick-Wolfenbüttel in 1523 after the Hildesheim Diocesan Feud. Wallenstein directed operations in the Harz foreland from here during the Thirty Years' War. Secularisation brought it to Prussia in 1802, and stones were later removed for domain buildings.

The name Vienenburg passed to the Reuschenberg family: in 1647 Field Marshal Johannes Ernst Freiherr von Reuschenberg zu Setterich was granted the Amt Vienenburg, and the title Drost zu Vienenburg was inherited within the family until about 1720. Their sons often lived at Vienenburg rather than at their ancestral Burg Setterich. The gatehouse preserves a Hildesheim coat-of-arms stone dated 1725.

The site is reachable on foot from town, and the tower offers a safe way to climb up and observe the surrounding landscape after renovation work. The best time to visit is on clear days when visibility extends across the wider region.

The 24 m bergfried has been renovated twice, in 1853/54 and again in 2010, and now serves as a viewing tower. Its entrance sits 8 m above the courtyard, so the original access was by ladder or wooden stair. The tower walls are 2.63 m thick and about 8 m across.